android: add Java-side support for browser compositor async readback

content/browser/renderer_host/compositor_impl_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/compositor_impl_android.h"
 
 #include <android/bitmap.h>
 #include <android/native_window_jni.h>
 
 #include "base/android/jni_android.h"
@@ skipping 420 matching lines @@
     host_->SetViewportSize(size);
   root_layer_->SetBounds(size);
 }
 
 void CompositorImpl::SetHasTransparentBackground(bool flag) {
   has_transparent_background_ = flag;
   if (host_)
     host_->set_has_transparent_background(flag);
 }
 
-bool CompositorImpl::CompositeAndReadback(void *pixels, const gfx::Rect& rect) {
-  return false;
-}
-
 void CompositorImpl::SetNeedsComposite() {
   if (!host_.get() || needs_composite_)
     return;
 
   needs_composite_ = true;
 
   // For explicit requests we try to composite regularly on vsync.
   should_composite_on_vsync_ = true;
   root_window_->RequestVSyncUpdate();
 }
@@ skipping 173 matching lines @@
 void CompositorImpl::OnVSync(base::TimeTicks frame_time,
                              base::TimeDelta vsync_period) {
   vsync_period_ = vsync_period;
   did_composite_this_frame_ = false;
 
   if (should_composite_on_vsync_)
     Composite(COMPOSITE_ON_VSYNC);
 }
 
 }  // namespace content